I've been thinking about running Docker on CoreOS and Project Atomic lately... While the deployment model would be pretty different to what we are used to, I have 50% of the work already done in docker-ovs so I was interested to see if my containers would work on a system with the Open vSwitch kernel module loaded...
As I'm a Mac User, I use boot2docker for all my docker-related things. It's also pretty easy to change the kernel config to allow the Open vSwitch module to be loaded.
Clone my fork
git checkout openvswitch
Build the iso
docker build -t boot2docker . && docker run --rm boot2docker > boot2docker.iso
Run boot2docker with the new iso
boot2docker destroy boot2docker init --iso="`pwd`/boot2docker.iso" boot2docker up
Load the Open vSwitch kernel module
boot2docker ssh sudo modprobe openvswitch exit
Run an Open vSwitch container
docker run -t -i --privileged=true davetucker/docker-ovs:2.1.2 /bin/sh export OVS_RUNDIR=/var/run/openvswitch sed -i s/nodaemon=true/nodaemon=false/g /etc/supervisord.conf supervisord
Test it out
ovs-vsctl add-br br0 ovs-vsctl show # This didn't work before ovs-dpctl show
This isn't a thorough test. I'd like to create some traffic and see the flows installed in the kernel but I'm just happy that
ovs-dpctl is working.
Based on my current understanding of OVS, it should be possible to just containerize the userspace agents and use the kernel module that has been in the upstream Linux kernel since 3.3. The one caveat here is that new features that are added to OVS may either have poor performance or be unsupported until an kernel module has been contributed upstream. However with OVS, VXLAN and GRE support already in the current stable kernel I think that is a compromise I can live with!
If you are still using docker-ovs for CI, this means that you can use the kernel datapath too and I'll be updating the docker-ovs README to explain how to do this in due course...
The one area that remains to be explored is to see if multiple containers can share the kernel module in the host system. Hopefully I'll find some time to explore that in the near future :)